Bug #20587: dir.c calls blocking filesystem APIs/system calls while holding the GVL

• Status: Open
• Assignee: -
• Target version: -
• Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN

[ivoanjo (Ivo Anjo)]

Hey! I work for Datadog on the Ruby profiler part of the datadog (previously ddtrace) gem.

While I was investigating https://bugs.ruby-lang.org/issues/20586, I spotted that there's a number of cases where, in dir.c, blocking system calls are being made (e.g. readdir(), opendir(), etc) without releasing the GVL.

This means that if they block for a long time (as happens in the gcsfuse example in https://bugs.ruby-lang.org/issues/20586 ), the Ruby VM will just be blocked and not make any progress.

The combination of not releasing the GVL + slow system calls actually makes the issue in https://bugs.ruby-lang.org/issues/20586 more likely to happen with the Datadog profiler, although even if the code releases the GVL the underlying issue could still happen, and this is why I decided to file this bug separately.

[ivoanjo (Ivo Anjo)]

• Subject changed from dir.c calls blocking system calls while holding the GVL to dir.c calls blocking filesystem APIs/system calls while holding the GVL